After some thought, I've decided on a combination of approaches to solve the motor / differential interference. First, I bought some aluminum 1.5" lift spaces and installed them this weekend (side note: I'm tired of wrestling these springs. This is the *last* time I remove / reinstall them...):
This shows the clearance gained by doing this:
That's without batteries installed, of course - with 500 pounds of lead in front, and with a new adjustable trackbar installed, I expect that clearance to shrink to about 1.5 inches (which, no surprise, is the height of the new spacer).
Next, I'll gain another inch by either rotating the motor 180 degrees or by moving the motor mounting points back (stay tuned...)
It's been really *cold* this week, so that is likely all until this weekend.